Automatic transmissions include a torque converter, which includes a pump and a turbine that cooperate to provide a fluid coupling for communicating torque between an engine and a drivetrain. During normal operation, when the fluid coupling of the torque converter is transmitting torque from the engine to the drivetrain, the fluid coupling of the torque converter dampens torsional vibration, i.e., torque fluctuation, between the engine and the drivetrain.
Some automatic transmissions are equipped with a lock-up clutch, which mechanically connects the pump and the turbine to mechanically transmit torque from the engine to the drivetrain. When the lock-up clutch is engaged, and the pump and the turbine are mechanically connected, the fluid coupling provided by the torque converter is unable to dampen torsional vibration. In order to dampen torsional vibration between the engine and the drivetrain when the lock-up clutch is engaged, the transmission may be equipped with a torsional vibration damper. The torsional vibration damper interconnects two different components of the transmission to dampen vibration therebetween. For example, the torsional vibration damper may interconnect the turbine and an input hub of the transmission to dampen torsional vibration from the engine when the lock-up clutch is engaged and mechanically connecting the pump and the turbine.